The study, published in Medicine & Science in Sports & Exercise, took a look at a lot of aspects of underwater treadmill training and its effects on adults. One major (and unexpected) finding was how aquatic treadmill training affected blood pressure. Sixty sedentary adults were randomly selected to be a part of either the land treadmill training group (LTM) or the aquatic treadmill training group (ATM) for 12 weeks. The maximal Bruce Treadmill test was performed before and after training and blood pressure was measured prior to, at the end of each stage and for 5 minutes following exercise testing. The maximal Bruce treadmill test is a standardized diagnostic tool used to evaluate cardiac function, which involves walking on a treadmill while being monitored by an electrocardiograph. Not only did they use this technical means of gathering data, they also went a step further and were able to get muscle biopsies from 12 of the participants. The muscle samples were tested for eNOS content (the controller of smooth muscle content).

The results of this 12 week study found that ATM, but not LTM, had a significant impact. It reduced resting diastolic blood pressure, exercise systolic blood pressure, diastolic blood pressure, mean arterial pressure, and pulse pressure during exercise and recovery. They also found that the ATM group also had an increase in skeletal muscle (but not the LTM group).

This is a big deal! We always knew that underwater treadmill training makes us feel great and we have known for a long time that runners and athletes use it for training because they feel it makes them stronger and recover faster. And we know that patients recovering from surgery, rehabbing from injury, or working to lose weight find amazing results from the water. But now we know WHY! This means that underwater training is truly affecting blood pressure and strengthening muscles.